Pantograph



Nov. 4, 1969 GLAVAN 3,475,819

PANTOGRAPH Filed Nov. 17, 1967 INVENTOR. IVAN GLAVAN Agent United States Patent 3,475,819 PANTOGRAPH Ivan Glavan, 1840 Victoria Park Ave., Scarborough, Ontario, Canada Filed Nov. 17, 1967, Ser. No. 684,021 Int. Cl. B431 13/10 US. Cl. 3325 6 Claims ABSTRACT 0F THE DISCLOSURE A pantograph having a frame consisting of a number of pivotally interconnected arms arranged in two sets, all the arms of one set being parallel to each other and all the arms of the other set being similarly parallel. Sleeves are provided at the ends of the arms to permit threaded portions of a stylus, tracing member, anchoring member and prop to be removably attached to the frame. The tracing member has a pin and a movable carriage. The threaded portion of the tracing member is associated with the carriage and when the pin contacts a drawing board, the carriage is urged upward by a spring within the carriage, thereby rotating the frame about the anchoring member and moving the stylus upwardly from the paper.

This invention relates to geometrical instruments and is particularly directed to pantographs.

In the drafting field, where it is desired to enlarge or reduce the size of a drawing, it is common to employ a pantograph. A pantograph, in its simplest form, is composed of two or more pivotally attached arms to which elements are fastened. These elements commonly are an anchoring member, stylus and tracing member. When the pantograph is fastened to a fixed point by means of the anchoring member, movement of the tracing member produce a corresponding but larger or smaller movement of the stylus. When the tracing member is moved about a drawing, the stylus reproduces the drawing in a different proportion.

Alteration of the proportion is normally effected by adjustment of the positions about which the arms pivot. There are normally a number of holes in the arms and a bolt is inserted in appropriate holes of intersecting arms to provide the required proportion. However, the holes normally enlarge with use of the pantograph and lateral movement of pivotally connected arms relative to each other cannot be prevented, Precise work with such a pantograph is therefore rarely satisfactory. In addition, adjustment'of a pivot point is time consuming. Means have been devised to overcome these problems, including a pantograph having a frame consisting of a large triangle and a number of smaller triangles within the large triangle. A number of points are provided to which the elements can be fastened. Such a pantograph provides the operator with a number of fixed accurate proportions from which he can choose a desired proportion. The number of possible proportions which can be obtained is limited, however, inasmuch as there is a limitation both in the interchangeability of the various elements and in the number of points to which the elements can be attached. Only by increasing the number of arms of the pantograph, and therefore its size, can the number of proportions be increased by this means.

It is accordingly an object of this invention to provide a compact pantograph which provides a large number of accurate proportions.

It is another object to provide a pantograph which permits the rapid alteration of proportions.

It is another object to provide a pantograph in which the stylus, when not in use, will not make unwanted marks on a paper.

According to the present invention, a large number of proportions can be quickly and accurately obtained by providing a pantograph having a stylus, an anchoring member, a tracing member, a frame consisting of terminal arms, a first set of parallel intermediate arms, a second set of parallel intermediate arms, the intermediate arms arranged between the terminal arms, all of the arms being pivotally connected at a sufficient number of their intersections to permit the frame to expand and contract and to cause the arms to maintain their parallel relationship when the frame is expanded or contracted, and means for removably attaching the stylus, anchoring member and tracing member to any of the arms. A further feature of this invention is that means are provided for raising the stylus from the paper when not in use to prevent the stylus from producing unwanted marks on the paper.

A fuller understanding of the invention may be had by referring to the following description and claims taken in conjunction with the accompanying drawing, in which:

FIGURE 1 is a top plan view of an embodiment of the pantograph frame;

FIGURE 2 is an elevation in section of the stylus;

FIGURE 3 is an elevation in section of the tracing member;

FIGURE 4 is an elevation partly in section of the anchoring member; and

FIGURE 5 is an elevation partly in section of a prop.

Like reference characters refer to like parts throughout the description of the drawing.

The pantograph illustrated includes a frame designated generally as 10, having ends generally designated 22 and 26 and sides 24 and 28.

Frame comprises terminal arms 12a, 12b, 13a, 13b and two sets of intermediate arms 14. For the sake of clarity the arms of one set are marked 14a and the arms of the other set 14b. All arms 14a are arranged parallel to each other and all arms 1412 are similarly parallel to each other. Arms 14a intersect arms 14b along three parallel imaginary lines as shown and are pivotally interconnected on their centre lines A-A at end points 16 and 18 and middle points 20.

Terminal arms 12a, 12b, 13a and 13b are arranged in pairs, one at end 26 of frame 10 and the other at end 22. One arm of each pair is parallel to one set of intermediate arms 14. For the sake of clarity the same letter 1s used to designate a parallel relationship between termlnal arms 12a, 12b, 13a and 13b as is used to designate a parallel relationship between intermediate arms 14 so that arm 12a at end 26 and arm 13a at end 22 are parallel to each other and parallel to arms 14a. Similarly, arms 13b, 12b and 14b are all parallel to each other.

Arms 12b and 13a at end 22 are pivotally attached to each other on their centre lines BB and CC respectively at and to intersecting arms 14:: and 14!; at points 17 and 19 respectively. Similarly arms 12a and 1312 at end 26 are pivotally attached to each other at 15 and to intersecting arms 14b and 14a at points 17 and 19 respectively.

The ends of intermediate arms 14 are rounded and apertures formed therein to form sleeves 30 and 32. Sleeves 30 and 32 are shown in plan in FIGURE 1 and it will be seen that the centres 31 and 33 of sleeves 30 and 32 respectively lie on centre line A-A. The inner wall of sleeves 30 and 32 are threaded for engagement with a stylus and tracing and anchoring members as hereinafter explained. Similarly, sleeves 34 and 36 are formed in the ends of terminal arms 12 and 13 opposite pivotal attachment 15 and centres 35 and 37 lie on centre line BB and CC respectively.

Sleeves 30, 32, 34 and 36 have equal internal diam- 3 eters and equal lengths. The number 58 in FIGURE 2 indicates the length of any of sleeves 30, 32, 34 and 36.

The stylus shown in FIGURE 2 is generally designated by the number 40. Stylus 40 comprises lead 42, base 44 and cap 46. Base 44 has a longitudinal opening 48 and at one end flexible fingers 50. When fingers 50 are inserted into cap 46, sloping walls 52 of cap 46 urge fingers 50 toward each other. It is evident that the further fingers 50 are inserted into the cap 46, the closer fingers 50 will be to each other. Lead 42 may therefore be firmly held in base 44 by fingers 50 by first inserting lead 42 into longitudinal opening 48 so that a portion of lead 42 is between fingers 50 and then inserting fingers 50 into cap 46 so that fingers 50 are urged together to engage lead 42. At the end of base 44 opposite fingers 50 is externally threaded portion 54.

Tracing member indicated generally as 60 comprises pin 62 and movable carriage 64. Carriage 64 has an externally threaded portion 76 and a longitudinal opening 74 to accommodate pin 62. Helical spring 65 is positioned about pin 62 within carriage 64. Spring 65 urges flange 70 attached to pin 62 away from cap 67. Thus, when threaded portion 76 is screwed into engagement with any one of sleeves 30, 32, 34 and 36 and when pointed portion 66 contacts a drawing surface, spring 65 will urge carriage 64 away from the drawing surface in a direction indicated by the arrow in FIGURE 3. Cap 67 and top 72 may be threadably connected to carriage 64 and pin 62 to permit removal and replacement of spring 65.

Anchoring member indicated generally as 80 comprises weight 82, threaded portion 84, pointed end 86 and base 88. At one end of base 88 are pins 90 which are intended to faciiltate the firm attachment of base 88 to the drawing surface and also permit the relatively easy removal of base 88 therefrom. At the other end of base 88 is a conical hole 92. Hole 92 is sufiiciently large to permit pointed end 86, when inserted therein, to oscillate slightly about apex 94 of hole 92.

Prop indicated generally as 100 comprises handle 102, threaded portion 104 and rod 106. When threaded portion 104 is screwed into engagement with any one of sleeves 30, 32, 34 and 36, rod 106 will contact the drawing board, thereby stabilizing frame 10.

Sleeves 30, 32, 34 and 36 are adapted to threadably receive threaded portions 54, 76, 84 and 104. As shown, the length of said threaded portions (shown as 56 in FIG- URE 2) is approximately double the length of sleeves 30, 32, 34 and 36.

The operation of the pantograph can best be understood by referring to frame shown in FIGURE 1. Frame 10 comprises twelve intermediate arms 14 and two pairs of terminal arms 12 and 13. On intermediate arms 14, the distance between centre 33 and end point 18 is intended to be one half the distance between centre 31 and end point 16, and the distances between end point 16 and middle point 20, and end point 18 and middle point 20 are equal and twice the distance between centre 31 and end point 16. It will be readily apparent that the distance between adjacent centres 31 and the distance between centre 35 and adjacent centres 31 will always be equal whether frame 10 is expanded or contracted. This distance is marked X on FIGURE 1. It will also be evident that the distance between adjacent ecntres 32 on intersecting intermediate arms 14 (marked Y) at end point 18 also is equal and one-third the distance between adjacent centres on non-intersecting arms 14 (marked 3Y).

The positions of stylus 40, tracing member 60 and anchoring member 80 will depend on the required amount of enlargement and reduction. If a drawing is to be enlarged, the distance between stylus 40 and anchoring member 80 must be greater than the distance between tracing member 70 and anchoring member 80 by an amount corresponding to the degree of enlargement; for example if the drawing must be enlarged five times, the distance between stylus 40 and anchoring member 80 must be five times greater than the distance between tracing member 60 and anchoring member 80. Similarly, if it is required to reduce the size of a drawing, stylus 40 will be positioned between anchoring member and tracing member 60, the distance corresponding to the degree of reduction. Of course, not only may stylus 40, tracing member 60 and anchoring member '80 be fastened to sleeves 30 and 34 at side 26, but also to sleeves 32 and 36 at side 24. t

It will be evident that the number of possible proportions is very large when frame 10 shown in FIGURE 1 is used. It is possible, for example, to convert an engineering scale to an architectural scale and vice versa. The following table provides an indication of the scales which may be converted. The figures in the third column represent the increase in scale. Thus if the distance between the anchoring member and the tracing member is one unit, the distance between the anchoring member and the stylus must be the number of units shown in the third column to achieve the desired degree of enlargement.

Engineers Scale Arele Ehiteet's Scanlargement After the positions have been chosen for stylus 40, tracing member 60 and anchoring member 80 to achieve the correct degree of enlargement or reduction, threaded portions 54, 76, 84 and 104 of each element are secured into engagement with the correct sleeves. It is evident from FIGURE 1 that arms 14a rest on arms 14b; thus the distance of sleeve 30 at the end of arm 14a from the drawing board will be greater than the distance of sleeve 30 at the end of arm 14b. Distance 56 of threaded portion 54 and similar distances of threaded portions 76, 84 and 104 must therefore be at least double distance 58 in order to permit adjustment of the lower ends of threaded portions 54, 76, 84 and 104 to approximately the same distance from the drawing board.

To operate the pantograph, base 88 is pressed into the drawing board at the required position and threaded portion 84 is screwed into engagement with one of sleeves 30, 32, 34 and 36. Pointed end 86 is then inserted into conical hole 88. Threaded end 54 of tracing member 40 is then screwed into engagement with one of sleeves 30, 32, 34 and 36 over the drawing to be reproduced so that point 66 of pin 62 contacts the drawing board. Threaded portion 54 of stylus 40 is then screwed into engagement with one of sleeves 30, 32,34 and 36 over the paper on which the drawing is to be enlarged or reduced in size. Lead 42 should be in proximity to, but not contact, the paper. Tracing member 60 is then grasped and downwardly directed force is then applied thereto to compress helical spring 65 sufficiently to cause carriage 64 to move downwardly toward the drawing board. Movement downward of carriage 64 causes frame 10 to rotate about anchoring member 80 and provision is made for slight oscillation of pointed end 86 about apex 94 of hole 92. When tracing member 60 as shown in FIGURE 3 is employed, anchoring member 80 must never be between stylus 40 and point 60. It will be understood that movement of carriage 64 of tracing member 60 toward the drawing board will cause a corresponding movement of stylus 40 and lead 42 will contact the paper. Thus, by properly adjusting the positions of tracing member 60 and stylus 40 within sleeves 30, 32, 34 and 36, only when tracing member 60 is being manipulated will lead 42 contact the paper. The finished drawing will therefore be free from unwanted marks.

Prop may be fastened to any suitable sleeve 30, 32, 34 or 36 to stabilize frame 10. It is preferred to employ at least one prop 100 at the side of frame 10 opposite the side at which stylus 40, tracing member 60 and anchoring member 80 are connected if they are connected at one side only.

The drawings forming a part of this application merely illustrate preferred embodiments of the instant invention. It will be readily appreciated that the stylus may consist of no more than a pen or pencil having a suitable provision for attachment to sleeves 30, 32, 34 and 36. Internally threaded rings may be threaded to the threaded portions of the members to stabilize them on the frame. Also, no provision may be made for urging frame upward when the pantograph is not in use, and therefore tracing member 60 may consist of a very simple pointed implement. Many other suitable means may be employed for attaching stylus 40, tracing member 60, anchoring member 80 and prop 100 to frame 10 including clips, nails, screws. In addition, the number of intermediate arms 14, the distance between end points 31, 33, 35 and 37 at middle points and 15 can be varied.

What I claim as new and desire to protect by Letters Patent of the United States is:

1. A pantograph including a stylus, an anchoring member, a tracing member, two pairs of terminal arms, each said pair being pivotally interconnected and spaced apart from theother said pair, a series of intermediate arms arranged in two sets of equal number between said pairs of terminal arms, one said set being parallel with one of said terminal arms in each said pair and the other said set being parallel with the other said terminal arm in said pair, said arms forming a frame having ends defined by said terminal arms and two sides defined by the ends of said arms, each said set intersecting both the other said set and said pairs of terminal arms; pivotal connections at all said intersections so that said frame will expand and contract and will cause said arms to maintain their parallel relationship when said frame is expanded or contracted; and means provided at both ends of said intermediate arms and the free ends of said terminal arms to permit removable attachment of said stylus, said anchoring member and said tracing member, said means being spaced apart from said pivotal connections, the distance between said attachment means on each said arm and the pivotal connection on said arm nearest thereto on each side of said frame being equal.

2. A pantograph as claimed in claim 1 wherein said attachment means comprises internally threaded sleeves.

3. A pantograph as claimed in claim 2, wherein said tracing member includes a pin, carriage and spring, said spring being positioned about said pin within said carriage and being adapted to urge said carriage away from a drawing board when said pin contacts the drawing board, one end of said carriage being externally threaded and adapted to mate with said internal threads of said sleeves.

4. A pantograph as claimed in claim 2 wherein said stylus includes a lead, base and cap, said lead being adapted to fit into a longitudinal opening within said base, said lead being secured by fingers at one end of said base which are brought into contact with said lead by insertion of said fingers into said cap, the other end of said carriage being externally threaded and adapted to mate with said internal threads of said sleeves.

5. A pantograph as claimed in claim 2 wherein said anchoring member includes a weight, threaded portion, pointed end and anchoring base, said weight, threaded portion and pointed end being connected in axial alignment with the threaded portion between the weight and the pointed end, said base having a conical hole therein; said pointed end being adapted to be received in said conical hole in said anchoring base so that said pointed end is free to oscillate slightly within said hole, said anchoring base having means for removably attaching said anchoring base to the drawing board, said threaded portion adapted to mate with said internal threads of said sleeves.

6. An anchoring member for use with a pantograph having a plurality of arms, said member including a weight, threaded portion, pointed end and anchoring base, said weight, threaded portion and pointed end being connected in axial alignment with the threaded portion between the weight and the pointed end, said base having a conical hole therein; said pointed end being adapted to be received in said conical hole in said anchoring base so that said pointed end is free to oscillate slightly within said hole, said anchoring base having means for removably attaching said anchoring base to the drawing board, said threaded portion adapted to mate with internal threads of a sleeve formed in an arm of said pantograph.

References Cited UNITED STATES PATENTS 834,470 10/ 1906 Hanssen. 938,936 11/ 1909 Ziegler. 978,012 12/ 1910 Foster. 1,496,889 6/1924 Kay. 2,810,960 10/ 1957 Johnson et a1.

FOREIGN PATENTS 11,128 1884 Great Britain. 734 1900 Great Britain. 671,981 9/ 1929 France.

HARRY N. HAROIAN, Primary Examiner 

